Removable capillary tube unit



Nov. 29, 1949 o. LINDGRIEN 2,489,914

REMOVABLE CAPILLARY TUBE UNIT Filed Oct. 2, 1945 2 Sheets-Sheet l INVENTOR. 65096, E O. R IIN REN Nov. 29, 1949 G. o. R. LINDGREN REMOVABLE CAPILLARY TUBE UNIT 2 Sheets-Sheet Filed Oct. 2, 1945 m w 0 m R 0 f w m. G,

Patented Nov. 29, 1949 REMOVABLE CAPILLARY TUBE UNIT George 0. R. Lindgren, Willoughby, Ohio. asaignor to The Weather-head Company, Cleveland, Ohio,

a corporation of Ohio Application October 2, 1945, Serial No. 619,738

.6 Claims. (Cl. 62-127) My invention relates to elements for fluid conveying systems, especially for refrigerating systerns.

The principal object of this invention is to facilitate the removal and replacement of the expansion element of a refrigerating system, such as a capillary tube expansion element, while maintaining a tight, leak-proof connection of the expansion element with the connecting portions of the refrigerating system in use.

Other objects are to avoid defrosting the evaporator by the admission of warm' liquid into the evaporator through the capillary tube in the period between cycles of operation of the compressor, to increase the capacity of the evaporator, by bringing the returning gas or semi-liquid from the evaporator into heat exchanging relation with the capillary tube, or with the liquid entering the capillary tube, or both.

Another object of this invention is to provide an adjustment for the restriction through a capillary tube expansion element whereby a single unit may be used with evaporators working at various different capacities.

' Other objects, features and advantages of the invention will be apparent from the following description of preferred embodiments thereof.

In the accompanying drawings:

Fig. 1 is a longitudinal section through a casing and removable capillary tube cartridge constructed according to this invention;

Fig. 2 is a similar view with parts in elevation showing the cartridge partly removed from the casing;

Fig. 3 is a longitudinal section similar to Fig. 1 showing a capillary tube cartridge with provision for adjustment of the length of the capillary tube; Fig. 4 is a front elevation of the assembly partly in section on the line 4-4 of Fig. 3;

Fig. 5 is a vertical section of the shell only taken on the line 5-5 of Fig. 3;

Fig. 6 is an end view of the inner end of the capillary tube unit; and

t Fig. 7 is a vertical transverse section of the tube unit taken on line 1-1 of Fig. 3.

.Like reference characters are utilized throughout the drawing to designate like parts.

The improved capillary tubing expansion unit is essentially formed as a removable unit within a fixed casing which is preferably a permanent part of the refrigerating mechanism when used in connection with such mechanism. This unit is interposed in the stream of refrigerating fluid which incidentally is filtered before it is received by the capillary tube. After passing through the 2 capillary tube or merely a section thereof, the fluid is then delivered in regulated quantities to the evaporator.

The simplest form of the invention illustrated in Figs. 1 and 2 comprises a casing ll adapted to be connected as a permanent part of a fluid conveying system such as a refrigerating system and having a boss 12 adapted to be connected in fluid-tight relation with the tube leading from the condenser and a boss l3 adapted to be similarly coupled to the tube leading to the evaporator of the refrigerating system. The removable cartridge includes a spool ll having end plates l5 and [6 about which is wound a capillary tube l'l. One end of the tube is open, as indicated at l8, and the other is sealed into a radial opening IS in the spool l4 leading into an axial recess 20.

The spool l4 and end plates l5 and I6 are fastened together in gas-tight relation, either by being formed integral with each other or by being welded or brazed together. as indicated in the drawings. The end plate I5 is provided with a sealing gasket 2| adapted to seal against a raised seat 22 formed on the end wall of the casing H and surrounding a bore 23 which communicates with the bore of the fitting boss I 3. A cylindrical filtering screen 24 is connected to the end plates 15 and I 6 and surrounds the capillary tube H. The end plate It is provided with a flange 25 fitting within and flush with the open end of the casing II, and a cap 28 carrying a sealing gasket 21 is arranged to be screwed on the open end of the casing I I so as to force the gasket 21 into sealing relation with the flange 25 and the end of the casing, and simultaneously to force the gasket 2| into sealing relation with the seat 22.

In assembled condition liquid from the condenser or compressor enters the casing l I through the fitting boss I 2, passes through the screen 24 and fills the spaces between the convolutions of the capillary tube II around the spool M. This fluid enters the open end of the capillary tube I8 and after passing therethrough is admitted through the recess 20 and the bore 23 to the tube leading to the evaporator connected to the fitting boss l3. Thus in assembled position the capillary tubing I1 is installed by leak-proof connections as a permanent part of the refrigerating system in the usual position between the compressor and the evaporator.

One of the service problems encountered with capillary tube expansion elements in refrigerating systems is that the opening in thetube tends to become restricted so that the tube becomes sluggish and must be replaced. In accordance with the present invention the tube is readily replaced by first relieving the pressure in the system and removing the screw cap 26 from the casing l i. The capillary tube cartridge can then be slipped out of the casing II as a unit, as illustrated in Fig. 2, and be replaced with a new cartridge which has been maintained in dehydrated condition so as to restore the system to its original efficiency very quickly thereby saving time and excessive cost of repair.

It is frequently desirable to adapt the removable capillary tube unit for use under varying conditions of load by utilizing a part only of its effective length. This may be accomplished by tapping the capillary tube as illustrated in Figs. 3 to 7 inclusive.

In this form of the invention the shell 28 has its inner end formed with a fitting boss 36, which is internally screw threaded for connection with the piping or other fitting leading to the evaporator proper. The inner end of the casing 28 has a port 31 surrounded by a raised seat 38. In the illustrated embodiment, two similar raised seats 38a which have no ports are formed on the inner end of the casing spaced 120 degrees on each side of the seat 38. The lower fitting boss 39 is also internally screw threaded for connection to the piping from the compressor or condenser and serves as an inlet for the refrigerating fluid.

A cap 4| is screw threaded over the open or outer end of the casing 28. This cap has an annular groove created by the presence of a central boss 42. This annular groove holds a; circular gasket 43 by which the open end of the casing is sealed.

The capillary tubing may be carried on a spool 44 shown with a solid core wwhich terminates at its inner end in a plate 45. The plate 45 has a spider 46 formed with radiating arms, in the present instance illustrated as three in number. The three arms of the spider have intermediate outlet openings or ports 41, 48 and 49. These openings pass through the inner end plate as shown in Fig. 3 and each is adapted to connect with the outlet port 31 of the casing. Each outlet opening is surrounded by a gas-tight gasket 50 adapted to seal against the seat 38 to connect the opening with the outlet port 31, or to seal against one of the seats 38a to close the o ening. The intermediate outlet ports 41, 48 and 49 connect with radial bores which are sealed at the ends of the spider arms by plugs 52. Each bore receives one or more ends of the capillary tubing.

On the end plate 45 of the spool diametrically opposite one opening or outlet there is firmly fixed a projecting pin 53 by which the spool may be selectively located against the inner end of the casing and with one of the outlet openings in registry with the port 31.

The opposite end 54 of the core carries a flanged plate 55. This fits the inner end of the casing closely and serves to center the spool in the casing. It will also be noted that the end of the flange plate fits against the gasket 43 thus sealing the space around the central portion of the spoo The capillary tubing consists of a plurality of separate lengths of tubing which have been in dicated as three in number and marked 51, 58 and 59. The inner tube 59 has one of its ends sealed into one arm of the spider 4'3 and communicating with the port 41, and its other end connected to another arm of the spider and communicating with the port 48. The doubled tube 59 is then wound spirally about the core 54. The intermediate length of tube 58 has one of its ends connected to the spider to communicate with the port 48 and the other of its ends connected to communicate with the port 49. The doubled tube 58 is then wound spirally about the core 54 in the opposite direction to the winding of the tube 59, forming an intermediate layer of tubing. The outer tube 51 has one end connected into the bore 5| which communicates with the port 49 and is wound singly about the core 54, forming the outer layer of tubing. The other end 60 of the tube 51 is left open and disposed adjacent the left hand end of the core 54, as shown in Fig. 3. A screen 6| surrounds the capillary tubing, as shown in Fig. 3, and serves to filter the liquid entering the casing 28.

Either one of the ports 41, 48 or 49 may be placed in communication with the outlet port 31 by selecting one of the three different positions of the cartridge. Registration of the ports is assured by providing the end wall of the casing 28 with three holes 62, 63 and 64 into any one of which the pin 53 carried by the spool end 45 may be inserted.

When the pin 53 is placed in the hole 62, in the position shown in Fig. 3, the port 41 is aligned with the outlet port 31 and the ports 48 and 49 are closed by the seats 38a. Thus liquid which enters the casing through the fitting boss 39 may pass through the screen 6| and into the open end 60 of the tube 51. After passing through the length of the capillary tube 51 the liquid passes the blocked port 49 and enters one end of the intermediate tubing 58. From the tubing 58 the liquid passes the blocked port 48 and enters one end of the inner layer of tubing 59. From the other end of the tubing 59 the liquid passes through the port 41, the outlet port 31 and the outlet boss 36 into the pipe leading to the evaporator. In this position the liquid is compelled to pass through all three lengths of tubing 51, 58 and 59, thus providing the greatest restriction for the smallest sized evaporator or the lightest loads. By turning the cartridge counterclockwise through the pin 53 may be entered in the hole 63. In this position the port 48 is aligned with the outlet port 31 and the ports 41 and 49 are closed. In this position the liquid enters the outer tube 51, passes the blocked port 49 and enters the intermediate tube 58 and from the opposite end of the tube 58 passes through the port 48 and thence to the outlet port 31. Thus the liquid must pass through two lengths of the capillary tubing 51 and 58 so that a medium restriction is provided for a medium load or medium sized evaporator. By turning the spool counterclockwise through another 120 the port 49 is aligned with the outlet port 31 and the ports 41 and 48 are closed. The liquid can no longer escape through the port 48 and thus enters one end of the capillary tubing 59 then passes through the port 49 through the outlet port 31. In this position the minimum restriction is provided for the heaviest loads or the larger evaporators.

With this arrangement it will be apparent that the amount of restriction in a given installation may be adjusted and also that a single standard cartridge may be manufactured for installation in refrigerating systems having evaporators of different capacities. Thus in the illustrated embodiment refrigerators might be made with three different sized evaporators and the single cartridge illustrated could be used in service to replace the capillary tube unit of any one of the three different sizes.

Various modifications and revisions of the described embodiment of the invention may be adopted without departing from the scope of the invention as defined in the following claims.

I claim:

1. In combination, a casing having an open end, a closure for said end, inlet means for introducing a refrigerating fluid into said casing, an outlet eccentrically positioned in the opposite end, a spool insertable into the casing through the open end, a number of capillary tubes coiled on said spool, a spool-end having an equal number of intermediate outlet ports, means for selectively connecting one of said ports to said outlet, one of said tubes being connected to one of said ports, and each of the other tubes connecting successive ports.

2. In combination, a casing having an open end, a closure for said end, inlet means for introducing a refrigerating fluid into said casing, an outlet eccentrically positioned in the opposite end, sealing means equally spaced with said outlet circumferentially of the end, a spool insertable into the casing through the open end, a number of capillary tubes coiled on said spool, a spool-end having an equal number of intermediate outlet ports, means for selectively connecting one of said ports to said outlet, one of said tubes being connected to one of said ports, and each of the other tubes connecting successive ports, the ports not being connected to said outlet being sealed by said sealing means.

3. In combination, a casing having an open end, aclosure for said end, inlet means for introducing an expansible fluid into said casing, an outlet for said fluid from the opposite end of the casing, a spool insertable into the casing through the open end, a number of capillary tubes coiled on said spool, a spool end having an equal number of intermediate outlet ports connected in series with said coils for delivering from one or more of them, and means for selectively connecting one of said outlet ports to the outlet in the end of the casing.

4. A capillary tube unit for a refrigeration system comprising a casing having inlet and outlet ports, a plurality of lengths of capillary tubing disposed in said casing, a member in said casing having a plurality of intermediate outlet ports equal in number to the number of tube lengths, said lengths of tubing being connected inseries by means of said member in the casing having a plurality of intermediate outlet ports with the first length having one end open to the casing inlet port and with the last length having its outlet end connected to the last of said intermediate outlet ports, said casing having means for sealing off all of said intermediate ports except wall thereof, a spool in said casing having end flanges fitting within said reduced bore sections, an outlet port in one of said end flanges aligned and sealed with said casing outlet port, a capillary tube coiled on said spool having one end open to said chamber and the other end connected to said flange outlet port, a filter screen surrounding said coiled tubing and attached at its ends to said spool flanges, said screengbeing spaced from the side wall of said cylindrical chamber intermediate its reduced sections whereby incoming fluid may pass through substantially the entire surface of said screen and bathe said coiled tubing, and a closure member for said casing that urges said spool toward said casing end wall.

6. A capillary tube unit for a refrigerator comprising a generally cylindrical casing having a closed end wall, said casing having a generally cylindrical chamber, an inlet port in the side wall of said casing and an outlet port in the end wall thereof, a spool in said casing having end flanges, an outlet port in one of said end flanges aligned and sealed with said casing outlet port, a capillary tube coiled on said spool having one end open to said chamber and the other end connected to said flange outlet port, a filter screen surrounding said coiled tubing and attached at its ends to said spool flanges, cooperating means do disposed on said spool flanges and at each end of said chamber and centering said spool in the chamber, said screen being spaced from the side wall of said cylindrical chamber intermediate its ends whereby incoming fiuid may pass across sub- 5 stantially the entire surface of said screen and through the latter and bathe said coiled tubing, and a closure member for said casing that urges said spool toward said casing end wall.

' GEORGE O. R. LINDGREN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,957,828 Greenwald May 8, 1934 2,021,452 Kevnzli et a1. Nov. 19, 1934 2,145,774 Muilly Jan. 31, 1939 

